UserDefaultsStorable

UserDefaultsStorable provides an easy, strongly-typed way to access properties in UserDefaults.

Summary

• Strongly typed: Access properties without type casting.
• Codable support: Support any types conform to Codable.
• Observation: Observe changes to properties with the given key.[

Requirement

• iOS 11.0+
• Xcode 11.4+
• Swift 5.2+

Installation

Cocoapods

pod "UserDefaultsStorable"

Swift Package Manager

.package(url: "https://github.com/mrfour0004/UserDefaultsStorable", from: "2.0.0")

Usage

To starting using UserDefaultsStorable, simply declare a UserDefaults property with a given key and a default value.

enum Defaults {
    @UserDefault(key: "username")
    static var username: String = "mrfour0004"
    
    // Of course type inference works as expected
    @UserDefault(key: "displayName")
    static var displayName = "mrfour"
    
    // If the stored type is Optional, initial value is not required as normal optional properties
    @UserDefault(key: "token")
    static var token: String?   
}

print(Defaults.username) // guest
print(Defaults.token)    // nil

Conforms types to UserDefaultsStorable

You may have custom types and want them can be stored in UserDefaults. Just conform them to the protocol UserDefaultsStorable, and implement the required userDefaultsBridge property.

struct Point {
    let x: Int, y: Int
}

extension Point: UserDefaultsStorable {
    static var userDefaultsBridge: UserDefautsBridge<Point> {
        UserDefaultsBridge(
            serialization: { point in
                return ["x": point.x, "y": point.y]
            },
            deserialization: { object in
                guard
                    let dict = object as? [String: Int]
                    let x = dict["x"] as? Int,
                    let y = dict["y"] as? Int
                else { return nil }
                return Point(x: x, y: y)
            }
        }
    }
}

If the type conforms to Codable as well, then there’s already a default implementation of userDefaultsBridge.

struct Point: Codable, UserDefaultsStorable {
    let x: Int, y: Int
}

enum Defaults {
    @UserDefault(key: "point")
    static var point: Point?
}

Observation

enum Defaults {
    @UserDefault(key: "username")
    static var username: String = "guest"
}

let observation = Defaults.$username.observe(withOptions: [.old, .new]) { change in
    print(change.newValue) // print Optional("guest")
    print(change.oldValue) // print Optional("mrfour")
}

let newValueObservation = Defaults.$username.observe { newValue in 
    print(newValue) // print Optional("mrfour")
}

Defaults.username = "mrfour"

License

UserDefaultsStorable is available under the MIT license. See the LICENSE file for more info.